I wish you luck with amplifying your Infinity speakers. I had four Kappa 682.7cf drivers in my 2006 Mustang... They were better than stock on radio power, but man did those fuggers make my ears ring when I amplified them.
First, I drove all four of them with roughly 100 watts RMS per driver from a RF 25 to Life Power 1000 at minimal gain, and that was WAY too much power for them. I am talking bleeding ear drums from the harsh highs!
Next, I removed the rear 6x8s and drove the door 6x8s with 125 watts per channel from a Soundstream Reference 700s, and that was still WAY too much power.
Lastly, I drove the remaining pair with 50 watts RMS per channel from two channels on a Lunar L450, and they were still too dang bright with the gains all the way down. The ultimate failure here was I had gone with an active HU and only fed the 6x8s from 315 Hz on up.